Economist has a very interesting article (Thanks Neil for pointing this to me) about use of mobile phones to transact money. By allowing this, it gives the facility to have your checkbook or online banking facilities to people even in remote rural parts of the underdeveloped world.
Moile phones are seeing very innovative applications in developing countries where they never used personal computers. In fact, it is very interesting to see that mobile phones first allowed these placed to leap frog (or just skip one generation) in communication area by bypassing land lines. Now the same device is likely to allow developing world to join the computing revolution directly in this advanced phase.
Mobile phones are proving to be one of the most transformative device ever developed.